Hot tapping seal assembly

ABSTRACT

A hot tapping assembly for hot tapping into a multiple string configuration to obtain access to the production tubing without removing outer layers of casing, the hot tapping assembly including a hot tapping clamp and a hot tapping seal assembly. In one embodiment, the hot tapping clamp includes a clamp plate having an access bore. The clamp plate can engage with an outer surface of a pipe. In another embodiment, the hot tapping seal assembly can engage with the hot tapping clamp, and includes a hot tapping tubular that can engage with the outer surface of the pipe through the hot tapping clamp&#39;s access bore.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/908,657, filed Jun. 3, 2013, now abandoned, which is a continuationof U.S. patent application Ser. No. 13/104,397, filed May 10, 2011(issued as U.S. Pat. No. 8,474,473 on Jul. 2, 2013), which is acontinuation of U.S. patent application Ser. No. 12/276,863, filed Nov.24, 2008 (issued as U.S. Pat. No. 7,938,137 on May 10, 2011), which is anonprovisional of U.S. Provisional Patent Application Ser. No.60/990,498, filed Nov. 27, 2007, each of which is incorporated herein byreference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable

REFERENCE TO A “MICROFICHE APPENDIX”

Not applicable

BACKGROUND OF THE INVENTION

1. Field of the Invention

The process of the present invention relates to gaining access to theproduction tubing to vent fluid pressure within the tubing. Moreparticularly, the present invention relates to a hot tapping system tovent pressurized fluids that eliminates the need to remove the outerlayer of casing to obtain access to the production tubing.

2. General Background of the Invention

The conventional hot tap system is designed to allow hot tapping of theouter casing. For the conventional hot tap system, the outer casing mustbe removed by a process known as wedding caking to proceed to the nextcasing string. The conventional hot tap system takes more time andequipment to complete the same job as the Multiple String Hot TapSystem. With more conventional Hot Tap System, the outer casing stringsmust first be hot tapped to release any trapped pressure in the casingor pump heavier fluid plug into the casing overcome the pressure. Oncethe pressure is released or controlled, a support structure can beattached to the outer casing for removal of a small section of the outercasing. This process is known as wedding caking; because each layer ofcasing is removed in layers. Once the small section of outer casing hasbeen removed, the next casing string can now be hot tapped to gaincontrol of this casing layer. The cycle of casing removal and hottapping is repeated until the production tubing is reached. Once theproduction tubing has been hot tapped and the well bore has beencontrolled, the damage well casing and wellhead can be removed.

A temporary wellhead is installed on the well using the remainingcasing. With the temporary wellhead in place, Plug and Abandonmentoperation can be started. The conventional hot tapping system could takeseveral weeks to complete all of the hot tapping and vent of casingstrings and production tubing. With a temporary wellhead installed,wireline or coil tubing operation can be used to lock open the SCSSV(surface control subsurface safety) with the manufacturers lock opentools. If there is pressure below the SCSSV, a bridge plug or tubingplug can be set to plug off the wellbore.

BRIEF SUMMARY OF THE INVENTION

What is provided is a method of hot tapping into a multiple stringconfiguration for obtaining access to the production tubing withoutremoving outer layers of casing by providing a multiple casing stringthat includes at least an outer casing and an inner casing or productionstring; mounting a clamp assembly around the wall of the outer casing;hot tapping a small opening through the outer casing wall to capture anypressurized fluid through the opening; cutting first and second largeopenings through the wall of the outer casing to access the innercasing, each opening being approximately 180 degrees from the otheropening; through the first opening, drilling a small hole through thewall of the inner casing to capture any pressurized fluid through theopening in the inner casing; and inserting an anvil through the secondopening to contact and stabilize the wall of the inner casing to preventthe casing from moving while the casing is drilled.

The multiple string hot tap system is a hot tapping system thateliminates the need to remove the outer layers of casing to obtainaccess to the production tubing. The system is designed around a uniquehot tap clamping system which has a 4 or 6 inch diameter bore in thecenter of the clamps. This bore in the center of the clamps will be usedto drill an access hole in the outer casing after the casing has beenhot tapped. The access holes are later used to hot tap the next casingstring.

The multiple string hot tap system eliminates the need for removal ofthe outer layers of casing to gain access to the inner layers of casingand the production tubing. The system designed around two clamps (afront clamp and a rear clamp). The two clamps are connected togetherwith four chains. The chains are tensioned by applying torque to thenuts on the chain connector. The tension on the chains is based on theouter casing or surface casing size, wall thickness and materialproperties. If the chains are tensioned too high, the casing will fallin collapse. The maximum hot tapping pressure for the assembly iscontrolled by the outer casing specification and the specific set up ofthe multiple string hot tap assembly. The maximum hot tapping pressurecan be increased by adding tension chains and increasing clamp bearingarea.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

For a further understanding of the nature, objects, and advantages ofthe present invention, reference should be had to the following detaileddescription, read in conjunction with the following drawings, whereinlike reference numerals denote like elements and wherein:

FIG. 1 illustrates a cross sectional view of the hot tap assembly in thesystem of the present invention;

FIG. 2 illustrates a front view of the hot tap assembly of the presentinvention;

FIG. 3 illustrates a rear view of the hot tap assembly of the presentinvention;

FIG. 4 illustrates a side view of the hot tap assembly of the presentinvention;

FIG. 5 illustrates a front view of the hot tap assembly of the presentinvention with front plate removed;

FIG. 6 illustrates a cross-section view of the hot tap assembly of thepresent invention with access holes;

FIG. 7 illustrates a cross-section view of the hot tap assembly of thepresent invention modified for inner casing hot tap;

FIG. 8 illustrates the hot tap assembly with front clamp modified withlarger bearing area;

FIG. 9 illustrates a side view of the modified hot tap assembly withfront clamp modified with larger bearing area;

FIG. 10 illustrates a cross-section view of alternative hot tap clampassembly of the present invention with larger access holes;

FIG. 11 illustrates a front view of alternative hot tap clamp assemblyof the present invention with larger access holes;

FIG. 12 illustrates a side view of alternative hot tap clamp assembly ofthe present invention with larger access holes; and

FIG. 13 illustrates a side view of the chain connector with hydrauliccylinder to better control the tensile/clamping loads in the system ofthe present invention.

DETAILED DESCRIPTION OF THE INVENTION

As will be seen more clearly in FIGS. 1 through 13, the method of thepresent invention relates to hot tapping a damaged oil well to releaseany pressure within the layers of casing or pipe, without removing theouter casing string to access inner casing strings and productiontubing. The novel method utilizes a multiple string hot tap system 10,also referred to as the novel System 10. The equipment is designed toallow hot tapping of each string of pipe in the completion withoutremoval of the support clamps.

In the present system, as illustrated in the various FIGS. 1 through 13,a front clamp 18 and a rear clamp 36 are connected together with fourtension chains 22. The chains 22 are tensioned by applying torque to thenuts 10 on the chain connectors 14. The tension on the chains 22 isbased on the outer casing size, wall thickness, and material properties.If the chains 22 are tensioned too high, the casing 24 will fall andcollapse. This amount of tension in the chains 22 will also control themaximum pressure that the hot tap assembly 10 can operate at or drill.

With the novel System 10, each casing string 24 is first hot tapped witha standard hot tap drill. The hot tap drill size is generally a ½ to ¾inch diameter. After each casing string has been drilled, access holes25 are bored. The access holes provide a way to extend the hot tap sealsaddle tubular 32 to the next casing string 26 or the production tubing28. The access holes 25 are generally 6 inches in diameter for casingsizes larger than 9 inches in diameter. For casing size smaller than 9inches in diameter, the access hole can be as small as 3 inches indiameter. The process is repeated for each inner casing string until theproduction tubing is reached without removing each casing string.

The novel System or method, as illustrated fully in the figures, andmore completely in FIG. 7, is designed around two clamps (a front clamp18 and rear clamp 36) as shown above in the drawing figures of the hottap assembly 10. The key to the system is the larger access bores 25 inthe two clamps 18, 36 which provide access to inner casing string 26 andproduction tubing 28. The major components of the novel System 10 wouldcomprise a front clamp 18 with large access bore 25; rear clamp 36 withlarge access bore 25; a front plate 30; a replaceable hot tap sealsaddle tubular 32; a front donut 31; a hot tapping seal ring 34; a rearplate 38; an adjustable rear support anvil 40; a rear donut 39; and anextension 44 for hot tap seal saddle tubular 32 positioning.

A critical feature of the multiple string hot tap system 10 includes aprovision to allow the stabilization or gripping the inner string 26 orpipe 28 for hot tap drilling. Through a second access hole 25, the rearsupport anvil 40 is installed 180° from the hot tap seal saddle tubular32. The casing/pipe 26 is firmly held in place. This eliminates the needto force to one side of the outer pipe 24 and insure that the inner pipe26 will not move during the hot tap operations. It also prevents thepipe 26 that is being hot tapped from grabbing the drill and failing inbuckling due to bending loads.

The multiple string hot tap system 10 shows the use of standard hot tapdrilling equipment. The front plate 30 which contains the hot tap sealsaddle tubular 32 has been designed to allow the uses of extensions 44to make up the additional distance to the next pipe. As stated earlier,the multiple string hot tap system 10 also provides a rear support anvil40 for stabilizing the inner string to be hot tapped. The rear supportanvil 40 has been designed to allow position adjustment by screwing theanvil 40 in or out of the rear plate 38. The multiple string hot tapsystem has a wider clamp to provide more support and bearing area. Theincreased bearing area provides higher operating pressure. The widerclamp can provide more resistance to bending load that is created by thehot tap drilling subassembly.

The present novel System 10 is connected using a combination of rollerchains 22 and chain connectors 14. The chains 22 are tensioned byapplying torque to the nuts 12 on the end of the chain connector 14. Thecondition of a coating of Teflon (a registered Trademark of DuPontCorp.) on the chain connector threads and the nuts 12 will control theactual tension in the chain 22. On chain connectors 14 and nuts 12, withnew Teflon coating, the coefficient of friction is low about 0.15 to0.05. On chain connectors 14 and nuts 12 with worn Teflon coatings, thecoefficient of friction is higher about 0.2 to 15. As the coefficient offriction rises, the tensile load for a specific torque falls. In thepresent hot tap system, the specified setting torque is about 50 ft-lbsto 105 ft-lbs to produce 5000 lbs. of clamping load in the chain. If ahydraulic cylinder 50, of the type illustrated in FIG. 13 was added tothe chain connectors 14, the clamping load can be controlled by applyingespecial hydraulic pressure. The modified chain connectors 14 wouldreplace each one of the four standard chain connectors 14 and nuts 12.This would eliminate the problems of accurately applying clamping loads.The clamping loads would be uniformly applied to each of the four chainin the hot tap clamp assembly.

As illustrated in the FIGS. 1 through 13, to carry out the method in themultiple string hot tap system 10 of the present invention, the firsteach casing string 24 is first hot tapped with a standard drill. Thestandard hot tap drill size is generally ½ to ¾ inch in diameter. Next,the multiple string hot tap clamp assembly 10 is installed on the outercasing 24 without the front plate 30 and the rear plate 38 in place. Inthe preferred embodiment, the centerline of the front clamp 18 and therear clamp 36 should be aligned to insure that correct support on futureoperations. The chains 22 should be tensed only enough to hold the clampassembly 10 in place. There is next provided a chain tensioning nut 12which should be torqued to the value specified preferably by theengineer in charge of the plug and abandon operation. The torque valueis based on the casing specification, hot tap pressure, and condition ofthe component of the hot tap assembly components. Next, the rear plate38 with the rear support anvil 40 is installed. The position of the rearsupport anvil 40 should be adjusted to insure that there is a minimumgap of 0.060 inch between the rear plate 38 and the rear clamp 36 whenthe retainer bolts 12 are installed. The retainer bolts 12 can bereplaced with 4 swing bolts and nuts. The swing bolts 12 are then pinnedto the rear clamp 36. In the next step, the front plate 30 with the hottap seal saddle tubular 32 is installed. The position of the hot-tapseal saddle tubular 32 should be adjusted to insure that the there is aminimum gap of 0.060 inch between the front plate 30 and the front clamp18 when the retainer bolts 12 are installed. The retainer bolts 12 maybe replaced with 4 swing bolts and nuts. The swing bolts are pinned tofront clamp. Again, the front retainer bolts 12 should be torqued to thevalue specified by the engineer in charge of the plug and abandonoperation. The torque value is based on the hot tap, pre-charge pressurethat is required. The pre-charge pressure is usually set higher than thecasing. The pressure provides an indicator when the hot tap drill breaksthrough the casing wall by dropping.

Next, the hot tap drilling sub assembly 10 is attached to the frontplate 30 and the hot tap saddle tubular 32 as illustrated. The hot tapdrilling subassembly would include the hydraulic drill or manual drillwith a drill bit; the pressure gauge to monitor hot tap drill pre-chargepressure; the pressure pre-charge control valve; the hot tap vent valve;and the union.

The hot tap drilling subassembly should be pressured up to thepre-charge value that was specified by the engineer in charge of theplug and abandon operation. The casing or pipe is drilled with ½ to ¾inch diameter bit when the bit breaks through the pipe wall, thepre-charge pressure will drop to a casing or pipe internal pressure. Thecasing or pipe internal pressure is vented and the hot tap drilling subassembly 10 is removed. Next, the front plate 30 with the hot tap saddletubular 32 is removed. The rear plate 38 with the hot tap rear supportanvil 40 is removed. The rail system, which is used to support andposition the large diameter drill (4 inch to 6 inch in diameter) or holesaw, is then installed on the outer casing 24 below the multiple stringhot tap clamp assembly 10. If the multiple string hot tap clamp assembly10 has to be moved or rotated to provide better support during hottapping of an inner casing string 26, the rail system can also be usedas a support while the clamp is repositioned.

Next, a probe is then run into the hot tap hole, and the location of thenext inner casing string or production tubing 26 is determined. If theinner casing or pipe 26 is not located on the center line of the hot tapclamps 18, 36, the hot tap clamps must be repositioned to ensure thatthe next string is located in the center line of the hot tap clamps. Twoaccess holes 25 are drilled in the outer casing 24. The first accesshole 25 is drilled through the clamp 18. The second access hole 25 isdrilled through the rear clamp 36. The access holes 25 will allow thehot tap saddle tubular 32 to be installed on the inner casing 26 and therear support anvil 40 to be installed. Before the rear plate 38 isinstalled, the rear support anvil 40 must be adjusted. When the rearplate 38 is installed and bolted in the rear hot tap clamp 36, the rearplate 38 should have an offset gap 41 with the rear clamp 36. The rearplate 38 is now installed.

Before the front plate 30 is installed, the hot tap seal saddle tubular32 must match the casing diameter or pipe diameter. The position of thehot tap saddle tubular 32 is adjusted by inserting the hot tap sealsaddle tubular extensions 44. When the front plate 30 is installed andbolted in the front hot tap clamp 18, the front plate 30 should have anoffset gap 33 with the front clamp 18. Next, the front plate 30 isinstalled. The front plate 30 retaining bolts or nuts 12 should be madeup to the torque value that is specified by the engineer in charge ofthe plug and abandon operation. The torque value is based on the hot tappre-charge pressure.

The hot tap drilling sub assembly 10 is attached to the front plate 30and the hot tap seal saddle tubular 32. The hot tap drilling subassemblywould include the hydraulic drill or manual drill with a drill bit; thepressure gauge to monitor hot tap drill pre-charge pressure; thepressure pre-charge control valve; the hot tap vent valve; and theunion. The hot tap drilling subassembly should be pressured up to thepre-charge value that was specified by the engineer in charge of theplug and abandon operation. The casing or pipe is drilled with a ½ to a¾ inch diameter bit. When the bit breaks through the pipe wall, thepre-charge pressure will drop to a casing or pipe internal pressure. Thecasing or pipe internal pressure is vented.

Following the venting of the internal pressure in the casing or pipe, asdescribed above, the process is repeated for each additional innercasing layer and production tubing until the well has been drilled andthe pressure vented or brought under control. For each casing layer, themultiple string hot tap seal saddle tubular 32 must be changed to matchthe casing or tubing diameter. In addition, seal saddle tubularextensions 44 must be added to compensate for the added distance fromthe multiple string hot tap clamp assembly 10.

FIGS. 8 through 10 illustrate front, side and overall views respectivelyof the multiple string hot tap system 10 having a front clamp 18designed to provide a larger bearing area 19, and for providing largeraccess holes 25 in the casing or pipe. The claim 18 is held in place bya series of four tension chains 22 secured to nuts 12.

FIGS. 11 and 12 illustrate front and side views respectively of yetanother modified manner in which to secure the front and rear 18, 36onto the wall of the casing 24 so as to provide a more stable means tohot tap the casing 24, and drill the larger access bores 25 in order tohave access to the next size casing or tubing 26 and production strings28.

As referenced earlier, FIG. 13 illustrates the use of a hydrauliccylinder 50 that would be engaged to the chain connectors 14, so thatthe clamping load can be controlled by applying especial hydraulicpressure. The modified chain connectors 14 would replace each one of thefour standard chain connectors 14 and nuts 12. This would eliminate theproblems of accurately applying clamping loads. The clamping loads wouldbe uniformly applied to each of the four chain in the hot tap clampassembly.

The following is a list of parts and materials suitable for use in thepresent invention.

PARTS LIST Part Number Description 10 multiple string hot tap system 12chain tensioning nut 14 chain connector 16 washer 18 front clamp 19larger bearing area 20 anvil 22 tension chain 24 surface casing 25access bores 26 production casing 28 production tubing 30 front plate 32hot tap seal saddle tubular 34 Teflon seal ring 36 rear clamp 38 rearplate 40 rear support anvil 44 extension 50 hydraulic cylinder

All measurements disclosed herein are at standard temperature andpressure, at sea level on Earth, unless indicated otherwise. Allmaterials used or intended to be used in a human being arebiocompatible, unless indicated otherwise.

The foregoing embodiments are presented by way of example only; thescope of the present invention is to be limited only by the followingclaims.

The invention claimed is:
 1. A hot tapping seal assembly comprising: aplate, the plate comprising a hot tapping bore extending through theplate and at least one side capable of engaging with a hot tapping clampassembly; a hot tapping tubular removably connected to the plate throughthe hot tapping bore, wherein an end of the hot tapping tubular extendsthrough the at least one side; and a hot tapping seal coupled to the hottapping tubular and capable of engaging with an outer surface of a pipe.2. The hot tapping seal assembly of claim 1, further comprising a donutcoupled to the at least one side of the plate and having a donut holecontinuous with the hot tapping bore, wherein the donut is sized toencircle the hot tapping tubular and mate with an access bore of the hottapping clamp assembly.
 3. The hot tapping seal assembly of claim 2,wherein, via the donut, the hot tapping seal is capable of articulatingabout an angle perpendicular to the plate.
 4. The hot tapping sealassembly of claim 1, wherein the hot tapping tubular is capable ofreceiving a seal extension to extend the distance between the hottapping seal and the plate.
 5. The hot tapping seal assembly of claim 1,wherein the hot tapping seal comprises a radius of curvaturesubstantially matching a radius of curvature of the pipe.
 6. The hottapping seal assembly of claim 1, wherein the hot tapping tubular andhot tapping seal are one assembly.
 7. A hot tapping assembly comprising:a hot tapping clamp comprising a clamp plate, the clamp plate capable ofengaging with the outer surface of a pipe and having an access bore foraccessing the outer surface of the pipe; and a hot tapping seal assemblycomprising a seal plate engaged with the clamp plate, a tubular memberhaving an end extending through the plate and the access bore, and a hottapping seal connected to the tubular member and capable of engagingwith the outer surface of the pipe.
 8. The hot tapping assembly of claim7, the hot tapping seal assembly further comprising an offset gapbetween the seal plate and the clamp plate when the hot tapping sealassembly and the clamp plate are engaged.
 9. The hot tapping assembly ofclaim 7, wherein the tubular member and the hot tapping seal are oneassembly.